Generator control system



June-15, 1943. H. BANY 2,321,969

GENERATOR CONTROL SYSTEM Filegl July 11, 1941 Inventor: Herman Bany,

i! is Attorney.

Patented June 15, 1943 2,321,969 GENERATOR. comoL SYSTEM Herman Bony, Lansdowne, 2a., assignor to General Electric Company, a corporation of New York Application July 11, 1941, Serialllo. 401,94:

3 Claims.

My invention relates to generator control systems and particularly to arrangements for causing the voltage of a direct current shunt excited generator to build up quickly to its normal value when the generator is being started provide an arrangement of apparatus for causing a shunt excited generator to build up its voltage quickly even though the generator has, for any reason, lost its residual magnetism since the last time it was operated.

My invention will be better understood from the following description when taken in connection with the accompanying drawing the single figure of which diagrammatically illustrates a direct current generator shunt field control system embodying my invention, and its scope will be pointed out in the appended claims.

Referring to the drawing, I represents a direct current generator which is provided with a shunt field winding 2 and which is arranged to be driven in any suitable manner. In the particular embodiment of my invention shown in the drawing, the generator I is arranged to be driven by an alternating current motor 3 which in turn is arranged to be connected to a suitable source of alternating current 4 by means of a switch 5.

In order to cause the voltage of the generator i to build up quickly even though the generator has lost its residual magnetism, I provide suitable rectifying means, such as a full wave rectifler :5, which has its input circuit connected to the secondary winding 8 of a potential transformer and its output circuit connected in series with the shunt field winding 2. The primar-y winding ill of the potential transformer 9 is arranged to be connected across one phase of the alternating current circuit l through the auxiliary contacts H on the switch 5 when it is closed. i also provide a control relay I2 which is connected in any suitable manner so that it is responsive to the voltage of the generator I exceeding a predetermined value. The relay I2, when in its deenergized position, closes its contacts I3, which are in the energizing circuit of the primary winding I I! of the potential transformer 9. When the voltage of the generator I exceeds a predetermined value so that the relay l2 closes its contacts l4, a shunt circuit is then completed across the output circuit of the rectifyi'ng means 1 so that it does not have to be of suflicient size to carry the normal exciting current of the exciter 2. Preferably the transformer O is so designed that only a small direct current from rest, and one object of my invention is to voltage relative to the normal voltage of the generator I is impressed across the input circuit of the rectifying means 1.

The operation of the arrangement shown in the drawing is as follows:

when it .is desired to start the generator I, the switch 5 is closed in any suitable manner so that the motor 3 is energized from the supply circuit 4 and causes the generator I to be accelerated from rest. The closing of the auxiliary contacts II 01' the switch 5 completes through the contacts II of the relay I2 an energizing circuit for the primary winding ll of the potential transformer 9. Consequently, a voltage is applied to the input circuit of the rectifying means I so that a direct current of a sufiicient magnitude flows in the proper direction through the field winding 2 and causes the voltage of the generator I to build up quickly as the speed of the generator increases. As soon as the generator voltage exceeds a predetermined value, the voltage relay I2 opens its contacts I3 and closes its contacts ll; The opening of the contacts I! deenergizes the primary circuit of the transformer 9 so as to render the rectifying means I ineffective to excite the shunt field winding 2 and the closing of the contacts II completes a shunt circuit around the rectifying means 1 in the circuit of the field winding 2.

While I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, and I therefore aimin the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, an alternating current cir cult, an alternating current machine having a direct connected generator, a shunt field winding for said generator, a circuit breaker for connecting said machine to said circuit, rectifying means having an input circuit and an output circuit, said output circuit being connected in series with said field winding so that said field winding is excited in response to the sum of the voltages of said generator and said output circuit, a relay responsive to the voltage of said generator for completing a shunt circuit around said rectifying means when the generator voltage exceeds a predetermined value, and means controlled by said clrcuit breaker and said relay for energizing said input circuit from said alternatingcurrent circuit only when said circuit breaker is closed and the voltage of said gener-' ator is below a predetermined value.

2. In combination, an alternating current circuit. an alternating current motor connected to a direct current generator having a shunt field winding, switching means connecting said motor to said circuit, rectifying means having an input circuit and an output circuit, said output circuit being connected 'in series with said field winding across the terminals of said generator, a relay responsive to the voltage of said generator for.

completing a shunt circuit around said rectifying means when the generator voltage exceeds a predetermined value, and means controlled by said switching means and said relay for energizing said input circuit from said alternating current circuit only when said motor is connected to said alternating {current .circiiit and the generator voltage is above a predetermined value.

3. In combination, an alternating current circuit, an alternating current machine having a direct connected generator, a shunt field winding for said generator, a circuit breaker for connecting said'machine to said circuit; rectifying means having an input circuit and an output circuit, said output circuit being connected in series with'said fleld winding so that said field winding is excited in response to the sum of the voltages of said generator and said output circuit, a relay responsive to the voltage of said generator, and means controlled by said circuit breaker and said relay for energizing said input circuit from said alternating current circuit only when said circuit breaker is closed and the voltage of said generator is below a predetermined value.

- HERMAN BANY. 

